Geophysical studies of the major sedimentary basins of the indian craton, their deep structural features and evolution

Geophysical measurements along tracks crossing some of the main structural features of the northern Baffin Bay shelf are described. The data consist of seismic reflection, seismic refraction, gravity, and magnetic measurements. Results in four areas—Lancaster Sound, Melville Bay, Smith Sound and Jones Sound—are presented. Magnetic and gravity data are used to define the extent of sedimentary basins in these areas. Seismic reflection measurements delineate the structural characteristics of the upper 2 km of the sedimentary strata and allow comparisons between them to be made. Seismic refraction measurements show that the upper 2 km of sediment exhibit low velocities—less than 3.2 km/s. Little deformation of the sediments is observed in any of these areas, however, the strata in Lancaster Sound and in the Melville Bay graben appear to have experienced less faulting than those in Jones Sound and Smith Sound. Normal faults are characteristic of the latter two areas. Jones Sound is a structurally complex area and is filled by a lesser thickness of sediments than is found in the other basins. These sediments are terminated near the entrance to the sound by Precambrian basement. A deeper sedimentary basin occupies Smith Sound and trends across the Nares Strait lineament. Although the data are insufficient to allow a detailed structural analysis of the strata in these regions, we speculate that the differences in sedimentary structures can be related to the formation of the Baffin Bay ocean basin.

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Towards an integrated restoration/forward geomechanical modelling workflow for basin evolution prediction

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2018018 ◽

2018 ◽

Vol 73 ◽

pp. 18 ◽

Cited By ~ 4

Author(s):

Anthony J.L. Crook ◽

Joshua Obradors-Prats ◽

Deniz Somer ◽

Djordje Peric ◽

Pete Lovely ◽

...

Keyword(s):

Seismic Data ◽

Niger Delta ◽

Sedimentary Basins ◽

Structural Features ◽

Production Costs ◽

Structural Restoration ◽

Additional Information ◽

Iterative Correction ◽

Optimal Resolution ◽

Material State

Many sedimentary basins host important reserves of exploitable energy resources. Understanding of the present-day state of stresses, porosity, overpressure and geometric configuration is essential in order to minimize production costs and enhance safety in operations. The data that can be measured from the field is, however, limited and at a non-optimal resolution. Structural restoration (inverse modelling of past deformation) is often used to validate structural interpretations from seismic data. In addition, it provides the undeformed state of the basin, which is a pre-requisite to understanding fluid migration or to perform forward simulations. Here, we present a workflow that integrates geomechanical-based structural restoration and forward geomechanical modelling in a finite element framework. The geometry and the boundary kinematics derived from restoration are used to automatically create a forward geomechanical model. Iterative correction may then be performed by either modifying the assumptions of the restoration or modifying the restoration-derived boundary conditions in the forward model. The methodology is applied to two problems; firstly, a sand-box scale benchmark model consisting of sand sediments sliding on silicon leading to the formation of a graben structure; secondly, a field-scale thrust-related anticline from Niger Delta. Two strategies to provide further constraint on fault development in the restoration-derived forward simulation are also presented. It is shown that the workflow reproduces the first order structural features observed in the target geometry. Furthermore, it is demonstrated that the iterative approach provides improved understanding of the evolution and additional information of current-day stress and material state for the Niger Delta Case.

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NEOTECTÔNICA DA PLATAFORMA BRASILEIRA: ESBOÇO E INTERPRETAÇÃO PRELIMINARES

Revista Geonomos ◽

10.18285/geonomos.v1i1e2.233 ◽

1993 ◽

Cited By ~ 16

Author(s):

Allaoua Saadi

Keyword(s):

Amazon Basin ◽

Sedimentary Basins ◽

Structural Features ◽

Drainage Pattern ◽

Seismological Data ◽

Continental Rifts ◽

Gravimetric Data ◽

Coastal Province ◽

Definition Of ◽

The Right

A number of significant informations about the evidences and characteristics of a neotectonic activity in the Brazilian Platform have been gathered in the last year in different parts of the country. These permit the definition of main structural features due to reactivation of Precambrian geossutures: Crustal Descontinuity of the Two Brazils (CDTB), Crustal Descontinuity of the Right Amazonian Margin (DCMDA), Minas- Alagoas Crustal Descontinuity (DCMA), Tocantins-Araguari Crustal Descontinuity (DCTA), Crustal Descontinuity of the Upper São Francisco (DCASF), Crustal Descontinuity of the Upper Rio Grande(DCARG), Crustal Descontinuity of the Pernambuco Lineament (DCLP), Crustal Descontinuity of the Midle-Upper Paraná (DCMAP), Crustal Descontinuity of the Paraíba do Sul (DCPS).In many of them, continental rifts and individual sedimentary basins have been generated. Some were submitted to a younger compression, resulting in its tectonic inversion. These main discontinuities control the macrorelief and the regional drainage pattern, as well as the orientation and subdivision of the main hidrographic basins.Blocks limited by these discontinuities are fragmented by faults of different types and sizes resulting in a regional structure alternating subsidence and uplift.The western extremity of the Amazon Basin is partially disrupted by blind inverse faults related to the Andean Orogeny. The central and Eastern areas are cut by Riedel Shears due to E-W dextral shearing.The oriental coastal province displays different patterns from south to north. The southern and southeastern regions, are dominated by Cenozoic uplift with tilting of blocks to W and NW and domnwarping of the off-shore blocks. In the Northeastern region morphological doming is related to transpressive conditions due to E-W dextral shears.The geological and seismological data indicate horizontal, roughly NW-SE oriented compressive stresse at least in the N, NE and Center- SE areas. Gravimetric data confirm the morphotectonic interpretation.

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Electron microscopy and diffraction studies of polyimides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074069 ◽

1983 ◽

Vol 41 ◽

pp. 28-29

Author(s):

O.C. de Hodgins ◽

K. R. Lawless ◽

R. Anderson

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Structural Features ◽

Inert Atmosphere ◽

Polyimide Films ◽

Resolution Electron ◽

The Matrix ◽

High Resolution Electron Microscope ◽

Diffraction Patterns ◽

Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

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Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074768 ◽

1983 ◽

Vol 41 ◽

pp. 194-195

Author(s):

D. F. Blake ◽

L. F. Allard ◽

D. R. Peacor

Keyword(s):

High Resolution ◽

Marine Invertebrates ◽

Sea Urchins ◽

Structural Features ◽

Sea Stars ◽

High Resolution Tem ◽

Relationship Of ◽

The Relationship ◽

Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

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Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053310 ◽

1982 ◽

Vol 40 ◽

pp. 118-119

Author(s):

U. Aebi ◽

P. Rew ◽

T.-T. Sun

Keyword(s):

Electron Microscopy ◽

Structural Organization ◽

Cell Types ◽

Structural Features ◽

Molecular Architecture ◽

The Past ◽

Keratin Filaments ◽

Different Types ◽

10 Nm Filaments ◽

Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

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Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069867 ◽

1978 ◽

Vol 36 (3) ◽

pp. 70-77 ◽

Cited By ~ 1

Author(s):

R.M. Glaeser ◽

S.B. Hayward

Keyword(s):

Diffraction Pattern ◽

Structural Information ◽

Structural Disorder ◽

Structural Features ◽

Biological Macromolecules ◽

Diffraction Intensity ◽

Object Structure ◽

Specimen Material ◽

Unit Cells ◽

Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

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Some Structural Features of Metaphase Chromosomes of Mice and Men

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060969 ◽

1967 ◽

Vol 25 ◽

pp. 190-191

Author(s):

Godfrey C. Hoskins ◽

Betty B. Hoskins

Keyword(s):

Electron Microscopy ◽

Electron Micrographs ◽

Structural Features ◽

Metaphase Chromosomes ◽

The Future ◽

Of Mice And Men ◽

Mouse Cells ◽

Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

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